Embodiments of the present invention relate to an extreme ultra violet (EUV) mask, and more particularly to an EUV mask for use in an EUV process to reflect a light.
As semiconductor devices are gradually reduced in size, many techniques have been developed in semiconductor fabrication technology to facilitate size reduction. Exposure process technology in particular has been greatly changed. Specifically, existing immersion technology for use in memory devices of 40 nm or less has reached limits, so many developers and companies are conducting intensive research into EUV lithography.
Unlike a conventional exposure process, EUV exposure is carried out using a light source having a very short wavelength of 13.5 nm, such that the EUV exposure technology is the most important fabrication technology in developing semiconductor devices having a critical dimension (CD) of 40 nm or less. However, since EUV exposure uses a light source producing light with a very short wavelength relative to existing exposure sources, it uses a reflection mask instead of a conventional transmission mask.
Specifically, the critical dimension (CD) of features on a semiconductor may be reduced so that they are smaller than an intended size, and features may generally be damaged by EUV and DUV (Deep Ultra Violet; 193 nm˜257 nm) light reflected from a black border region overlapped with an exposure region within one wafer.